Mast cell tumours are a rare group of diseases that is caused by the accumulation of mast cellsthe basic structural and functional unit of all living things in tissues and organs. Mast cells are a type of white bloodthe red bodily fluid that transports oxygen and other nutrients around the body cell in the immune system that mediate inflammatory responses, such as allergic reactions.
Mast cell tumours are slightly more common in females, however anyone can develop this disease. The average age of diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results varies by subtype.
Types of Mast Cell Tumours
There are several types of mast cell tumours, which are often categorised by their location and presentation in the body.
Cutaneous Mastocytosis
Cutaneous Mastocytosis are mast cell tumours that are found in the skin. This disease is generally found in children under two, and often has a good prognosisto predict how a disease/condition may progress and what the outcome might be. In some cases, cutaneous Mastocytosis may recur or develop into systemic Mastocytosis. Cutaneous Mastocytosis are thought to be benignnot cancerous, can grow but will not spread to other body parts conditions, but they can become malignantcancerous, may grow and spread to other areas of the body if left untreated.
Solitary Cutaneous Mastocytoma
A solitary cutaneous mastocytoma is a common form of cutaneous Mastocytosis that appears on the skin as a singular lesion. It resembles a persistent insect bite in appearance, and is most commonly found in infants less than three months old. Solitary cutaneous mastocytomas generally have an excellent prognosis.
These tumours can be further described by their shape:
- Macule (maculopapular cutaneous Mastocytosis).
- Plaque (plaque-type mastocytoma – rare).
- Nodular mastocytoma (very rare).
Maculopapular Cutaneous Mastocytosis
Maculopapular cutaneous Mastocytosis, also known as urticaria pigmentosa, is the most common type of cutaneous Mastocytosis. They generally occur in infants around three to four years old, however they can be found in adults. In children, Maculopapular cutaneous Mastocytosis can go away on their own, and often have a good prognosis. Adults who develop this condition may go on to have a systemic Mastocytosis.
Diffuse Cutaneous Mastocytosis
Diffuse cutaneous Mastocytosis is a rare form of cutaneous Mastocytosis that appears as a diffuse redness of the skin (or erythrodermaan inflammatory skin condition characterised by intense and widespread redness of the skin) with various degrees of blistering. It is most commonly found in infants under the age of two, however adults and adolescents can also develop the disease. Diffuse cutaneous Mastocytosis is not usually aggressive, and can have a good prognosis.
Telangiectatic Cutaneous Mastocytosis
Telangiectatic cutaneous Mastocytosis, also known as telangiectatic macularis eruptive perstans (TMEP) is a very rare form of cutaneous Mastocytosis that is characterised by small, irregular spots and brown, widened blood vessels (or telangiectasiasmall, widened, red/purple blood vessels that are visible on the surface of the skin, also known as spider veins) on the trunk, arms and legs. Unlike most forms of cutaneous Mastocytosis, this disease is more common in adults, and may not have as good of a prognosis as other subtypes.
Systemic Mastocytosis
Systemic Mastocytosis are mast cell tumours that develop in extracutaneous tissuea group of cells that work together to perform a function (or outside of the skin). This disease is generally found in adults, and are generally more aggressive than cutaneous Mastocytosis. Many types of systemic Mastocytosis are benign, however, some are malignant.
Indolent Systemic Mastocytosis
Indolent systemic Mastocytosis is the most common type of systemic Mastocytosis, and is the least aggressive. Unlike other subtypes of this disease, indolent systemic Mastocytosis can affect the skin, and may have maculopapular skin lesions. This disease can have a good prognosis when caught early.
Rare subtypes of indolent systemic Mastocytosis include:
- Isolated bone marrowsoft, spongy tissue found in bones that makes blood cells Mastocytosis.
- Well-differentiated Mastocytosis.
Smouldering Systemic Mastocytosis
Smouldering systemic Mastocytosis is a less common form of systemic Mastocytosis, and generally have more groups of mast cells present. This disease can affect the bone marrow, and can cause enlargement of the spleen and/or the liver. Smoldering systemic Mastocytosis tends to be more aggressive, and may not have as good of a prognosis as other mast cell tumours.
Aggressive Systemic Mastocytosis
Aggressive systemic Mastocytosis is a rare and highly aggressive disease that causes an impairment or loss of organ function due to mast cell clusters. This disease is most commonly found in people over 60, and tends to be very aggressive. Aggressive systemic Mastocytosis may not have as good of a prognosis as other mast cell tumours.
Systemic Mastocytosis with an Associated Hematologic Neoplasm
Systemic Mastocytosis with an associated hematologic neoplasm occurs when a patient meets the criteria for systemic Mastocytosis, as well as a hematologic neoplasm. In most cases, the associated condition is either myeloproliferative neoplasms (MPNs) or Myelodysplastic syndromes (MDSs).
For more information on MPNs and MDSs, please refer to the Rare Cancers Australia KnowledgeBase.
Mast Cell Leukaemia
Mast cell leukaemiacancer of blood and/or blood forming tissues (MCL) is a very rare and very aggressive subtype of systemic Mastocytosis. MCL occurs when abnormal mast cells invade the bone marrow, and begin to circulate through the blood. This disease is likely to metastasise, and may not have as good of a prognosis as other mast cell tumours.
Mast Cell Sarcoma
Mast cell sarcomas are a very rare and very aggressive disease that is not classified as a cutaneous or systemic form of Mastocytosis. They are solid tumours that arise from mast cells infiltrating bone and soft tissuetissue/the material that joins, holds up or surrounds inside body parts such as fat, muscle, ligaments and lining around joints. This disease is likely to metastasise, and may not have as good of a prognosis as other mast cell tumours.
Treatment
If a benign mast cell tumoura tissue mass that forms from groups of unhealthy cells is detected, it will not require stagingthe process of determining how big the cancer is, where it started and if it has spread to other areas unless it progresses into an advancedat a late stage, far along disease.
If a malignant mast cell tumour is detected, it will be staged and graded based on size, metastasiswhen the cancer has spread to other parts of the body, also known as mets,and how the cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodea small lump or mass of tissue in your body) indicates whether the cancer has spread to nearby lymph nodessmall bean-shaped structures that filters harmful substances from lymph fluid.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localisedaffecting only one area of body cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Gradea description of how abnormal cancer cells and tissue look under a microscope when compared to healthy cells I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, age, stage of disease and overall health.
Treatment for mast cell tumours may include:
- Allergy medicationsmedication used to reduce allergy symptoms, including sneezing, runny nose and itchy/watery eyes., potentially including:
- Antihistamines.
- Epinephrine/Adrenaline (EpiPens).
- Leukotriene antagonists.
- Sodium cromoglycate.
- H2 blockers.
- Omalizumab.
- Photodynamic therapya procedure that involves inserting a light-sensitive drug (photosensitiser) to shrink and damage cancer cells when exposed to a light source.
- Proton pump inhibitorsmedication that reduce the amount of stomach acid produced by the body, potentially including:
- Omeprazole.
- Lansoprazole.
- Pantoprazole.
- Corticosteroidsa type of anti-inflammatory medication that is used to treat inflammation.
- KIT inhibitorsmedication that targets the c-KiT receptor to inhibit tumour growth and survival.
- Targeted therapymedication that targets specific molecular features of cancer cells.
- Interferon therapya treatment that uses synthetic versions of proteins made by the body to fight cancer.
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Bone marrow transplanta procedure that involves replacing unhealthy bone marrow with healthy bone marrow.
- Stem cell transplanta procedure that involves replacing unhealthy blood-forming cells (stem cells) with healthy stem cells.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Risk factors
Because of how rare mast cell tumours are, there has been limited research done into the riskthe possibility that something bad will happen factors of these diseases. However, a genetic mutation of the KIT gene has been confirmed as a risk factor.
Symptoms
Many people with a mast cell tumour may appear asymptomatic in the early stages of disease. As the tumour progresses, some of the following symptoms may appear.
Symptoms of Solitary Cutaneous Mastocytoma
Symptoms of a solitary cutaneous Mastocytoma may include:
- A firm macule, plaque or node.
- A lesion that is red, pink, yellow, or brown in colour.
- Itching – especially when rubbed.
- Darier sign (lesion that urticates or blisters after rubbing).
- Skin flushing.
Symptoms of Maculopapular Cutaneous Mastocytosis
Symptoms of a maculopapular cutaneous mastocytoma in children may include:
- Brown patches and abnormal freckles.
- Darrier sign.
- Blisters.
Symptoms of a maculopapular cutaneous mastocytoma in adults may include:
- Abnormal-looking lesions.
- Itchy lesions.
- Flushing of the skin.
- Hypotensionlow blood pressure.
- Anaphylactic shock.
- Diarrhoeafrequent discharge of watery or loose stools from the body.
- Blood in stoolwaste product from the bowel sent to the anus for removal; also known as faeces or poo.
Symptoms of Diffuse Cutaneous Mastocytoma
Symptoms of a diffuse cutaneous mastocytoma may include:
- Erythroderma.
- Widespread blistering of the skin.
- ‘Leathery’ appearance and texture of the skin.
- Darrier sign.
- Itching.
- Blistering.
- Hypotension.
- Diarrhoea.
- Blood in stool.
- Anaphylactic shock.
Symptoms of Telangiectatic Cutaneous Mastocytosis
Symptoms of a telangiectatic cutaneous mastocytoma may include:
- Small, irregular spots on the skin.
- Telangiectasia.
Symptoms of Indolent Systemic Mastocytosis
Symptoms of an indolent systemic mastocytosis may include:
- Skin flushing.
- Diarrhoea.
- Skin lesions similar to those produced by a maculopapular cutaneous mastocytoma.
- Splenomegalyenlargement of the spleen.
- Hepatomegalyenlargement of the liver.
Symptoms of Smouldering Systemic Mastocytosis
Symptoms of a smouldering systemic mastocytosis may include:
- Splenomegaly.
- Hepatomegaly.
- Lymphadenopathyswollen lymph nodes/glands, also known as adenopathy.
- High levels of tryptase in the blood.
- Abnormal level of mast cells in bone marrow.
Symptoms of Systemic Mastocytosis with associated haematological neoplasm
Symptoms of a systemic mastocytosis with an associated haematological neoplasm may include:
- Splenomegaly.
- Hepatomegaly.
- Lymphadenopathy.
- Abdominal pain.
- Nauseato feel sick or likely to vomit and/or vomiting.
- Headaches.
- Dizziness.
- Hypotension.
- Flushing of the skin.
In addition to these symptoms, patients may also present with the symptoms of their associated condition.
Symptoms of Aggressive Systemic Mastocytosis
Symptoms of an aggressive systemic mastocytosis may include:
- Organ dysfunctionimpaired or abnormal function; not working properly (symptoms vary based on organ affected).
- Leukopeniaa low level of white blood cells in the blood.
- Anaemiaa condition where there aren't enough red blood cells in the blood, causing fatigue, weakness and pale skin and affecting how the body responds to infection.
- Thrombocytopenialow levels of platelets in the blood.
- Malabsorption of nutrients.
- Skin flushing.
- Hypotension.
- Anaphylactic shock.
- Diarrhoea.
- Blood in stool.
- High levels of tryptase in the blood.
Symptoms of Mast Cell Leukaemia
Symptoms of a MCL may include:
- Weakness and/or fatiguea state of extreme tiredness or exhaustion, can be physical or mental.
- Syncopefainting or passing out.
- Flushing of the skin.
- Fever.
- Tachycardiaa rapid heart rate; clinically defined as a rate of more than 100 beats per minute.
- Unexplained weight loss/loss of appetite.
- Diarrhoea.
- Nausea and/or vomiting.
- Itchiness.
- Skin blisters.
- Bone pain.
- Hypotension.
- Peptic ulcer disease.
Symptoms of Mast Cell Sarcoma
Symptoms of a mast cell sarcomacancer arising from bones and/or soft tissue may include:
- Flushing of the skin.
- Fever.
- Malaisegeneral feeling of being unwell.
- Fatigue.
- Tachycardia.
- Massa growth of cells that come together to make a lump, may or may not be cancer in affected area.
Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have a mast cell tumour, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Blood teststesting done to measure the levels of certain substances in the blood.
- Imagingtests that create detailed images of areas inside the body tests, potentially including:
- Ultrasounda type of medical imaging that uses soundwaves to create detailed images of the body .
- Bone scana type of medical imaging that uses a radioactive tracer to detect bone conditions or abnormalities.
- Bone marrow aspirationa procedure that involves inserting a needle into the hipbone (or the breastbone in some cases) to remove samples of solid and liquid bone marrow..
- Biopsyremoval of a section of tissue to analyse for cancer cells.